JPH08251539A - Apparatus and method for recording for variable speed reproducing in video cassette recorder for digital hdtv - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide device/method for extracting speed change data from a digital HDTV signal and recording it in the specified region of a tape in digital VCR recording/reproducing the digital HDTV signal compressed with MPEGII as a reference. SOLUTION: The digital HDTV signal is separated into normal reproduction data and speed change reproduction data. Separated speed change reproduction data are stored in plural frame buffers 154A and 154B. Speed change reproduction data of a multi-frame is superimposed and recorded along a track so that tracking is started at an arbitrary position at the time of speed change reproduction and picture quality can be improved at low double speed. Speed change reproduction data is recorded in a safe track region so that speed reproduction data is safely detected even if a head non-linearly executes tracking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a recording method for extracting data from a digital HDTV signal and recording it in a specific area in a digital VCR for recording / reproducing a digital HDTV signal compressed based on MPEGII. In particular, the digital HDTV signal is separated into normal reproduction data and variable speed reproduction data, the separated variable speed reproduction data is stored in a plurality of frame buffers, and the variable speed reproduction data output from the plurality of frame buffers is stored. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus and method for variable speed reproduction of a VCR for digital HDTV, which is capable of obtaining good image quality during variable speed reproduction by alternately recording data alternately along each track.

[0002]

2. Description of the Related Art A stationary digital VCR uses a method of compressing a transmitted analog TV signal by its own encoder and then recording and reproducing, and a method of recording and reproducing the transmitted digital TV signal as it is. . High-definition TV (hereinafter referred to as HDTV) signal of a completely digital system (for example, Grand Al which is an HDTV system in the United States)
The latter method is used for recording the liance format), but in this case, the encoder of its own is unnecessary, only the interface circuit is added, and there is no distortion due to encoding, so the transmission image quality is maintained as it is. . However, such a transparent recording method (Transpar
ent Recording Method),
Image quality deterioration occurs remarkably in variable speed reproduction, which is an important function in the current VCR, particularly in forward / reverse reproduction.

As a means for solving such a problem, in a digital VCR for transparently recording a bit string which is an HDTV signal, the data rate required for recording the input bit string is actually the data on the tape. Since it is smaller than the recordable recording rate,
A method for performing variable speed reproduction by recording variable speed reproduction data in a tape area corresponding to the difference is being sought.

That is, this method is a method in which a variable speed reproduction bit string is extracted from an input HDTV bit string, recorded in a variable speed reproduction area, and then a variable speed image is composed only of this data during variable speed reproduction. Therefore, the recording track is a normal reproduction area (hereinafter,
A normal area) and a variable speed reproduction bit section (hereinafter referred to as a trick area) for recording the extracted variable speed reproduction bit string.

In a general azimuth recording type VCR, since the tape is moved at the same speed as during recording during normal reproduction, the head travels along the track of the tape as shown in FIG. A track of the head is formed along the track. However, during variable speed reproduction in which the moving speed of the tape is different from that during recording, the head travels across a plurality of tracks and a locus traversing the tracks is formed, as shown in FIG. 19B.

Therefore, during variable speed reproduction, only partial data is extracted from each track of the same azimuth and reproduced.
Also, the HDTV bit string is an example of compressed bits,
However, it is encoded in an intraframe (Intraframe
Only the coded bit string can be independently decoded. As a result, in a VCR in which HDTV bit strings are sequentially recorded, the data reproduced during variable speed reproduction is burst, that is, only a part of each track is reproduced, and the variable speed image is only an intra frame bit string among these data. Composed. Therefore, the variable-speed image to be reproduced is a mosaic image in which the entire screen is not updated and is partially restored, and it is difficult to reproduce the variable-speed image with good image quality.

As shown in FIG. 20, a conventional home digital VCR recording device for variable speed reproduction receives an HDTV bit string including video data, audio data, etc., and is a basic unit for recording and reproducing the VCR. A sync block unit 1 for converting to a sync block form, a buffer 2 for temporarily storing the sync block output from the sync block unit 1, the HDTV bit string, and decoding only the video bit string of the HDTV bit string. , A video decoder for separating a bit string encoded into an intra frame among the video bit strings output from the transport decoder 3, and a bit string separated by the video header decoder 4. To recognize each codeword contained in A variable length decoder 5 that performs variable length decoding, and a shift data extraction unit 6 that separates only the direct current (DC) component and the low frequency component that are important data from each codeword output from the variable length decoder 5 And a transport encoder 7 for packetizing the variable speed reproduction video bit string obtained from the speed change data extraction unit 6 to have a format similar to a normal reproduction bit string, and a bit string output from the transport encoder 7 for synchronizing blocks. Sync block unit 8 for converting into a form, a buffer 9 for temporarily storing the sync block output from the sync block unit 8, a track recording format unit 10 for providing recording timing corresponding to various recording formats, and a track recording format unit Depending on the recording timing applied from 10, the normal bit string of the buffer 2 or the buffer Composed of multiplexer 11 for outputting a speed reproduction bit string of 9 error correction encoding unit (not shown).

The operation of the conventional home digital VCR recording apparatus having the above-described structure will be described in detail with reference to the accompanying drawings. The input HDTV bit string is supplied to the sync block unit 1 and, as shown in FIG.
After being converted into a sync block form, which is a basic unit for recording and reproducing data, the data is stored in the buffer 2 and the multiplexer 1
At 1, it is appropriately multiplexed with the variable speed reproduction bit string. Further, the input HDTV bit string sequentially passes through a transport decoder 3, a video header decoder 4, a variable length decoder 5, a shift data extraction unit 6, a transport encoder 7, a synchronization block unit 8 and a buffer 9 to form a variable playback bit string. To be done.

That is, in order to extract the variable speed reproduction data,
First, the transport decoder 3 starts with an HDT containing a video bit string, an audio bit string, and an additional data bit string.
The transport packet of the V bit string is decoded to separate only the video bit string, and the separated video bit string is output to the video header decoder 4. Next, the video header decoder 4 separates a bit string of an intra frame that can be independently decoded from the input video bit string and outputs it to the variable length decoder 5.

Since the HDTV bit string is variable length coded to obtain a high compression rate, variable length decoding is performed so that each code word can be recognized from the bit string.
Next, the shift data extraction unit 6 separates only the DC component and the low frequency component, which are important data, from each codeword included in the intra frame. That is, since the size of the tape area allocated to the variable speed reproduction area is limited,
Only the components that have a high contribution to the formation of the variable-speed image are extracted, so that the resolution of the reproduced variable-speed image is lower than the resolution during normal reproduction.

The transport encoder 7 forms the variable-speed reproduction video bit string obtained in the above process into a bit string conforming to the HDTV bit string standard (Syntax), and forms a transport packet into a format like a normal reproduction bit string. The converted sync block unit 8 reconstructs the input bit string into a sync block and applies it to the buffer 9.

The normal reproduction bit string and the variable speed reproduction bit string obtained by the above process are multiplexed by the multiplexer 11 according to the recording timing signal output from the track recording format unit 10, and then the error correction coding unit (see FIG. (Not shown). Here, the recording timing signal is a control signal suitable for a recording format of a normal reproduction bit string and a variable speed reproduction bit string which are respectively recorded in a normal area and a trick area of the tape.

When data is recorded in the normal area or trick area on the tape, the amount of trick area is different for each VC.
It is determined by the recording rate of R, and the position of the trick area on the track is determined by each shift realization algorithm. The amount and position of such a trick area is directly related to the image quality of the image reproduced at variable speed, and affects the multiple speed reproduction function and the tracking means of the head.

As an example of setting such a trick area, as shown in FIG. 22 (A), a trick plate rack system in which a trick area is assigned along a trajectory reproduced by a head at each speed factor, and FIG. As shown in (B), a method is possible in which the start, middle, and end portions of each track are assigned to the trick area regardless of the double speed number, and the same bit string is duplicatively recorded in several adjacent track units.

Generally, in a home digital VCR, 2
〜3 types of variable speed reproduction are performed, and the above-mentioned FIG.
2 (B) is a system considering x3, x9, and x27 double speed, respectively.

[0016]

However, in such a conventional variable speed reproduction system, when the variable speed reproduction data is positioned on the track, the variable speed image can be formed only when the head starts tracking at a specific position. There is a drawback that a tracking algorithm such as servo control is additionally required.

In the case of the trick plate rack system in which the trick area is assigned along the track reproduced by the head at each multiple speed, the variable speed reproduction data corresponding to each multiple speed is arranged by the limited tracking start position of the head. During playback, the double-speed data is played after the head is placed at the tracking start position that matches the double-speed number, so there is a drawback that an additional tracking algorithm for shifting is required, and it is suitable for each double-speed number. Since the recording positions should be assigned, the complexity of the hardware increases, such as complicated formatting algorithms and memory.

In this way, at the time of double speed, since the restriction condition that the head tracking start position should always be at a specific position is eliminated, the loss of double speed image quality is accepted, that is, the number of bits allocated per screen of the double speed image is reduced. Or reduce the frame rate of double-speed video (the number of screens played per second), assign the start and middle end of each track to the trick area regardless of the double speed, and assign the same bit string to several adjacent track units. In the case of the method of redundant recording, the amount of data that can be reproduced on one track in the case of a predefined maximum speed number (for example, at × 17 times speed,
By repeating the recording operation for each track for a certain period (for example, about 17 tracks) for about 32 synchronization blocks per track (for example, about 17 tracks), a double-speed image can be formed even if the shift is started at an arbitrary position. However, in this method, since the variable speed reproduction data is recorded redundantly, the allocated variable speed region is used inefficiently, and the image quality determined by the maximum speed number is continuously applied even when the speed is low. Therefore, there is a drawback that improvement in image quality cannot be expected.

Therefore, it is an object of the present invention to perform multi-frame variable speed reproduction data more efficiently along a track so that tracking can be started at an arbitrary position during variable speed reproduction and the image quality improvement can be compensated at a low speed. Another object of the present invention is to provide a recording device for variable speed reproduction of a VCR for digital HDTV which is redundantly recorded. Another object of the present invention is to perform variable speed reproduction of a digital HDTV VCR which records variable speed reproduction data in a safe trick area so that the variable speed reproduction data can be detected stably even if the head tracks on a non-linear line. To provide a recording device for.

[0020]

The present invention for achieving the above object includes a normal reproduction bit string processing unit for converting an input HDTV bit string into a VCR recording format and supplying a normal reproduction bit string. The system decoder unit for separating only the video bit string from the transmission layer of the HDTV bit string, and the variable speed reproduction data is extracted from the video bit string separated by the system decoder unit so that the extracted variable speed reproduction data fits the video syntax. A video bit string processing unit for converting to, a system encoder unit for reconfiguring the variable speed reproduction data output from the video bit string processing unit according to the header information output from the system decoder unit into a transport packet that is a transmission standard, The variable speed playback data output from the system encoder section. Data into a VCR recording format, and then stores it in a corresponding frame buffer respectively, and normal reproduction data output from the normal reproduction bit string processing section or variable speed reproduction output from the recording format processing section. It is characterized in that it is composed of a track recording format section for selecting the use data at an appropriate timing.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. A recording apparatus for variable speed reproduction of a VCR for digital HDTV according to the present invention is shown in FIG.
As shown in, a normal reproduction bit string processing unit 110 for converting the input HDTV bit string into a VCR recording format and outputting a normal reproduction bit string, and an input for receiving an HDTV bit string including video, audio and additional data. ,
The transmission layer (la) of the input HDTV bit string
system decoder unit 120 that separates only the video bit string from Y.), and important data is extracted from the bit string of the intra frame that is the variable speed reproduction data in the video bit string separated by the system decoder unit 120, and the extracted data Video bit string processing unit 130 for converting to match the syntax of the video bit string
And a system encoder unit 140 that reconfigures the bit string output from the video bit string processing unit 130 into a transport packet format that is a transmission standard according to the header information decoded by the system decoder unit 120, and the system encoder unit thereof. A recording format processing unit 1 for converting the variable-speed reproduction bit string output from 140 into a VCR recording format and storing it in a corresponding frame buffer.
50, a normal reproduction bit string (NB) output from the normal reproduction bit string processing unit 110, or a variable speed reproduction bit string (VBA, VBA, output from the recording format processing unit 150).
VBB) is selected at an appropriate timing and is recorded on the tape.

The normal reproduction bit string processing unit 110 includes an error correction coding unit 111 for adding a redundant bit to an input HDTV bit string to overcome an error that may occur in the recording and reproducing processes, and a header / tape mechanism. Normal interleaver 11 performing interleaving to overcome the generated burst error
2 and the bit string output from the normal interleaver 112, the synchronization signal (SYNC) and the identification signal (I
It is composed of a sync block forming unit 113 for adding d) to form a sync block and a buffer 114 for temporarily storing the output of the sync block 113.

The system decoder unit 120 includes a PID (Package) of a link layer included in an HDTV bit string input in a packet format.
t Identification Data) information is recognized to separate the video bit string, and the PSI (Program Specific) is extracted from the input HDTV bit string.
ation Information), PES (Pi
A transport decoder 121 for extracting system header information, such as a picture element stream, and the transport decoder 12.
1 and a buffer 122 for temporarily storing the header information output from the first header.

The video bit string processing unit 130 extracts the intra-frame bit string from the video bit string output from the system decoder unit 120, and the video header decoder 13 thereof.
1 output sequence or GOP (Group
Of Picture) A buffer 132 for storing header information, an A frame memory 133A and a B frame memory 133B for storing a bit string of an intra frame output from the video header decoder 131, and the A frame memory 133A and B frame memory 13
3B, a variable length decoder 134 for decoding the bit string output from the 3B by a variable length method, a buffer 135A for storing picture header information decoded by the variable length decoder 134, and a slice decoded by the variable length decoder 134. A buffer 135B for storing header information and macroblock coding information, and a codeword of each block included in the bit string decoded by the variable length decoder 134, have already set important data for the structure of the shift image. A run length code word selection unit 136 that selects the number of run length code words, and an EOB (End Of Bloc).
k) EOB insertion section 137 for adding a code, and a byte alignment section 1 for arranging each byte so that the extracted variable speed reproduction bit string has the same configuration as the HDTV bit string.
38 and variable-speed reproduction bit string formation for reconfiguring the bit string output from the run-length codeword selection unit 136 using the header information stored in the buffers 132, 135A, and 135B so as to match the syntax of the HDTV video bit string. And a section 139.

The system encoder unit 140 has a preset bit rate control unit 142 for adjusting the bit rate to be recorded, and a null packet (null p) under the control of the bit rate control unit 142.
stuffing (stuffi)
ng) unit 143 and a transport encoder 141 that reconstructs the bit string output from the variable speed reproduction bit string forming unit 139 into a transport packet that is a transmission standard using the headers PSI and PES stored in the buffer 120. Composed.

The recording format processing unit 150 provides the transport encoder 141 with redundant bits for error correction.
Error correction coding unit 151 to be inserted into the bit string output from the error correction coding unit 151, a trick interleaver 152 that interleaves the output bit string of the error correction coding unit 151, and the trick interleaver 15
A synchronization block forming unit 153 for converting the second output bit string into a synchronization block form, and the synchronization block forming unit 15
It is composed of A frame buffers and B frame buffers 154A and 154B for respectively storing the shift images for each frame applied from No.3.

The track recording format section 160 includes a track recording format section 162 for generating timing so that a normal reproduction bit string or a variable speed reproduction bit string is selected on the basis of a head switching pulse, and the track recording format section 162. The multiplexer 16 that selects the normal reproduction bit string output from the normal reproduction bit string processing unit 110 or the variable reproduction bit string output from the recording format processing unit 150 by control and outputs the selected variable reproduction bit string to the modulation unit (not shown).
1 and 1.

The operation and effect of the present invention thus constructed will be described in detail below with reference to the accompanying drawings. HDT
In a home-use digital VCR that records a V bit string by a transparent recording method, there is a difference between the size of a tape area required for recording input data and the size of a tape area where data can be actually recorded. ,
In the present invention, the variable speed reproduction data is recorded in the tape area corresponding to the difference. For example, GA (Grand Allian)
In the case of the HDTV bit string according to the (ce) system, the total data rate is about 21.5 Mbps, and of the data of such bit string, the data to be actually recorded is about 19.3 Mbps.

Therefore, a sync code (SYNC), an identification code (ID), and an error correction bit are added to the HDTV bit string input at a data rate of 19.3 Mbps to make the VCR.
When converted to recording format, the data rate is about 26.2Mbps
Therefore, the variable speed reproduction data is recorded in the trick area of the tape at a recording rate of about 30.8 Mbps to about 4.6 Mbps.

Here, as shown in FIG. 2, the basic specifications of a home-use digital VCR can be applied to the present invention. However, of the 352 synchronous blocks for each track, 48 synchronous blocks are assigned to the trick area. The data for variable speed reproduction uses a data rate of about 3.93 Mbps. A 2 × 2 CH head as shown in FIG. 3 can be applied to the present invention, and A and A ′ and B and B ′ are heads of the same azimuth.

The present invention is not limited to the azimuth recording method and can be applied to other recording formats as well, but for convenience of explanation, the azimuth recording method will be described as an example. FIG.
(A), FIG. 4 (B), and FIG. 4 (C) are each x2 speed,
The locus of the head at x4 speed and x6 speed is shown, and the hatched area in the figure corresponds to the area that can be reproduced at each speed. However, it is assumed that the maximum effective track deviation at which data can be detected is 50% of the track pitch.

At N times speed, the minimum reproduction area that can be reproduced on each track is given as follows. L: Number of sync blocks per track N: Double speed number Therefore, in a system with 352 sync blocks per track and a 2 × 2 CH head, the number of sync blocks reproduced per track at each double speed is shown in FIG. Calculated as shown.

The method of positioning the trick area on the track of the tape is as follows. However, for convenience of explanation, ×
Considering only 2x4x6x speed, it is assumed that 2x2CH head and 352SBS per track.
The tape transfer speed at x2, x4, and x6 speeds is a constant multiple during recording, and the head drive clock is phase-corrected (ph
The head tracking is always synchronized with the same azimuth because it is controlled by as locking. Therefore, since the position of the reproduced data is fixed by each speed factor, it is compensated that the data recorded at this position is reproduced for that speed number. Therefore, by assigning these positions to the trick region, the variable speed reproduction data of the double speed can be detected and reproduced for an arbitrary double speed number.

However, at other speeds, the head does not pass the trick area for an arbitrary speed, so that detection of recorded data is not guaranteed, so the trick area is set to an area that can always be reproduced even at multiple speeds. It should be. When the head starts tracking on an arbitrary track at x2, x4, and x6 speeds, the position of the reproducible sync block on the track is as shown in FIG. 4D. It is as shown in FIG. 6 when the position of is displayed by numbers.

If, for each of the three types of double speeds, the reproduction overlapping region is assigned to the trick region, the variable speed reproduction data is always detected at the double speed. Therefore, assuming that the maximum speed is 6 times, the minimum area (hereinafter, MRA: Minimum Recover)
ry Area) is about 18 sync blocks, and when tracking is started at an arbitrary position, there are 6 MRAs that cross one track.

For example, as shown in FIG. 4C, when the reproduction area is considered centering on the position of the reference track at the time of x6 speed, the MRA1 has a "2-1" position when the A head starts tracking. This is the area to be played and MRA2
Is an area which is reproduced when the A head starts tracking at the "1-11" position.
RA4, MRA5 and MRA6 are "1-9",
The areas are reproduced when the A head starts tracking at the "1-7", "1-5", and "1-3" positions. Therefore, by repeatedly recording the variable speed reproduction data at the MRAi (i = 1, 2, ..., 6) position of each track, the variable speed reproduction data is reproduced even if the tracking for the double speed reproduction is started at an arbitrary track position. it can. Also, such M
RAi is a reproducible area for all the double speeds of x2, x4, and x6, so that a plurality of double speed reproductions are possible.

Since the variable speed reproduction area per track is 48 synchronization blocks, each MRA in one track is
8 sync blocks are recorded in i as variable speed reproduction data. At this time, since 8 sync blocks in each MRAi are arranged in a relatively stable tracking area, the head becomes non-linear at double speed. Even if the tracking is performed, the variable speed reproduction data can be normally reproduced. That is, FIG. 7 is an example showing a variable speed reproduction data recording position with respect to tracking non-linearity, and eight synchronous blocks which are variable speed reproduction data are of each MBAi (i = 1, 2, ..., 6). Position it in the center. FIG. 8 shows an example of a trick area in consideration of the above conditions for each track.

The operation of the recording apparatus for variable speed reproduction of a digital HDTV VCR according to the present invention, to which such a variable speed reproduction data recording method is applied, will be described with reference to the accompanying drawings. First, the error correction coding unit 111 adds a redundant bit such as a parity bit to an input HDTV bit string and outputs it as a measure against an error that occurs in the recording and reproducing process, and the normal interleaver 112 uses a head / tape mechanism. Interleaving is performed to overcome a burst error generated by the sync block forming unit 11 and a synchronization signal and an identification signal (ID) are added to the interleaved bit string.
3 is added to form a sync block, and the sync block thus formed is stored in a buffer 114 for storing a normal reproduction bit string so that it can be recorded on the tape at an appropriate timing. At this time, the data interleaved by the normal interleaver 112 is data for the normal reproduction bit string, and the interleaving format is different from the interleaving format for the variable speed reproduction bit string.

On the other hand, as shown in FIG. 9, the transport decoder 121 receives the HDTV bit string input in the form of a transport packet, recognizes the PID header of the link layer contained in the transport packet, and Determine if the PID header is a video ID. Next, during encoding, necessary header information (PSI) (PES) is stored in the buffer 122, and the separated video bit string is applied to the video header decoder 23.

The operation of the video bit string processing unit 130 for extracting the variable speed reproduction bit string actually recorded on the tape from the video bit string separated by the transport decoder 121 and reconstructing it into the recording format will be described below. is there. The video header decoder 131 analyzes the video syntax of an intra-coded bit string of the video bit string input from the transport decoder 121, extracts the bit string, and then extracts the GOP (Group O).
For a bit string whose f Picture is variable, a PCT (P
image-coding-type) information is used to separate the intra-coded bit string.

That is, as shown in FIG. 11, when the GOP is variable and the sequence start code is not the picture start code, the GOP header is the buffer 132.
Stored in and the picture coding type is "0".
If it is 01 ″, the input bit string is the one that has been intra-frame coded, and thus is stored in the A frame memory 133A or the B frame memory 133B.

However, since an intra frame appears periodically for a bit string whose GOP is fixed at N,
However, after recognizing the picture start code, the intra frame bit string can be divided by a simple count. For example, when the GOP is 15, an intra frame exists every 15 frames. That is, as shown in FIG. 12, when the sequence start code is detected from the video bit string and the detected sequence start code is not the picture start code, the GOP header is stored in the buffer 132 so that it is used by the transport encoder 141. Stored. Since the sequence start code is the picture start code and the bit string of the picture corresponding to a multiple of N is the intra frame, the bit string of the picture is the A frame memory 13
It is stored in the 3A or B frame memory 133B. That is, the sequence information and the GOP header information from the video bit string are stored in the buffer 132 and applied to the variable speed reproduction video bit string forming unit 139 to form the variable speed reproduction video bit string.

Here, in order to prevent overflow,
The A and B frame memories 133A and 133B have a structure capable of storing a maximum amount of data generated when image information is encoded into an intra frame. When the video bit string is input from the video header decoder 131 to the A frame memory 133A, the B frame memory 133
The video bit string output from B is the variable length decoder 13
4, the A and B frame memories 133A and 133B can correspond to the bit amount of the intra frame variably generated and its timing, and also serve as a front end buffer of the variable length decoder 134. To do.

Since the HDTV bit string is variable length coded to obtain a high compression rate, the variable length decoder 134 is used.
Recognizes each codeword from the video bit string, and thus decodes the intra frame bit string input from the A frame memory 133A or the B frame memory 133B into a variable length method. Then, the variable length decoder 134
Of the output information of, the picture header of the intra-coded bit string is stored in the buffer 135A,
The slice header and the encoded information of the macroblock are stored in the buffer 135B and input to the variable-speed reproduction video bit string forming unit 139 at an appropriate timing.

Since the size of the trick area set on the tape is limited, the run length code word selection unit 1
36 is the DCT of the block included in each intra frame
Of the coefficients, only the components having a high contribution to the variable speed image, that is, the direct current component and the low frequency component, which are important data, are extracted from the codeword of each block as the variable speed reproduction data. By the way, since the HDTV bit string is generally variable-length coded, the run-length code word selecting unit 136 cannot actually extract exactly how many DCT coefficients, but only how many run-length codes are extracted. . Moreover, it is not the number of DCT coefficients but the number of run-length codes that determines the bit amount of the extracted data.

At this time, the number of DC components and run length codes extracted from each block is determined by the number of run length code words applied from the bit rate control unit 142 in order to control the amount of generated bits. It EOB (E
The nd Of Block) inserting unit 137 adds an EOB code (for example, code 10 or code 0110) after the extracted DC component and run length code word in order to match the video syntax to each block.

Byte Alignment (Byte Ali
The gnment) unit adjusts the variable speed reproduction data so that each start code is placed on a byte boundary on the video syntax of the HDTV bit string. That is, the input HDTV
The bit string is byte-aligned, but in the case of the bit string extracted by the variable speed reproduction data, the input H
Since the structure is different from that of the DTV bit string, a new byte alignment is required.

Therefore, the bite alignment section 138
As shown in FIG. 13, after extracting the variable speed reproduction data in each slice by checking the slice start code, a byte pointer (BP) is provided for each of the 8-bit DC component bits and the number of run length code words. ) Is added, and a “0” hit is added so that the slice start code is located on a byte boundary.

Next, the video bit string forming section 139
As shown in FIG. 16, buffers 132, 135A, 1
35B, the header information and the variable length reproduction video bit string output from the run length code word selection unit 136 are transferred to the EOB insertion unit 137 and the byte alignment 1
Under the control of 38, it is reconfigured so as to conform to the syntax of the HDTV video bit string.

At this time, the sequence header and GOP header input from the buffer 132 are placed at the front of each variable speed reproduction frame. That is, sequence information and GOP header information are intermittently present in the input HDTV bit string, but the user can start the variable speed reproduction at any time, and the sequence header is reproduced until the start of the variable speed reproduction. Since there is no correlation with the variable speed reproduction data, sequence information and GOP header information are inserted in each frame in the variable speed reproduction bit string.

In general, when a variable-speed reproduction bit string is input, the HDTV video decoder resets the contents of the buffer and the register at that time, so a sequence header is inserted for each frame to initialize the decoding variable. Is desirable. Next, the transport encoder unit 141 is used for reconstructing the variable speed reproduction video bit string extracted through the variable speed reproduction video bit string formation unit 139 into a transport packet which is a transmission standard. The trick mode flag, which is a flag for indicating that the bit string input to the HDTV video decoder at the time of reproduction is a variable speed reproduction bit string, using the PSI and PES header information applied from the buffer 122, is "1". Is set.

Since the trick area assigned to one frame for variable-speed video is fixed (for example, about 576 kbps), the amount of the variable-speed reproduction bit string to be extracted must also be within this range. Therefore, the bit rate control unit 142 controls the amount of bits extracted as the variable speed reproduction data by adjusting the number of run length codes selected for each block. That is, assuming that one frame includes M slices and the bit rate is controlled in units of N slices, if the track area assigned to one frame is L,
It is desired that an average of (L × N / M) bits be detected in N slices.

Therefore, if the bit amount actually generated for every N slices is larger than the average generated bit amount, the number of run length code words is reduced, and if it is smaller than the average generated bit amount. Increase the number of run length codewords. If an underflow occurs, the stuffing unit 143 adjusts the bit amount by using a null packet. Also, at the time of overflow, only the overflowed bit amount is not transmitted.

Next, the error correction coding unit 151 receives the video bit string reconstructed from the transport packet output from the transport encoder 141, and adds redundant bits for error correction to the input bit string. The trick interleaver 152 performs interleaving to overcome the burst error, and the sync block forming unit 153 converts the input bit string into a sync block, and then the sync block forming bit string is appropriately matched with the normal reproduction bit string. The synchronous blocked bit string is switched 15 so as to be selected at the timing.
4 to the A frame buffer 154A and the B frame buffer 154B.

As shown in FIG. 15, the multiplexer 161 outputs the timing signals (NORMAL), (TRICKA), (TR) output from the track recording format section 162.
ICKB) according to the normal reproduction bit string processing unit 110.
The normal reproduction bit string (NB) output from the A frame buffer 154A, the variable reproduction bit string output from the A frame buffer 154A, or the B frame buffer 154B output from the variable reproduction bit string (VBB) is selected.

That is, when the trick area and the normal area for each track are assigned as shown in FIG. 16A, the track recording format section 162 outputs the head switching pulse (HSP) as shown in FIG. 16B. FIG. 16C for selecting a normal reproduction bit string (NB) as a reference
16 (D) for selecting a timing signal (NORMAL), a variable speed reproduction bit string (VBA), and FIG. 16 (D) for selecting a timing signal (TRICKA) and a variable speed reproduction bit string (VBB). The timing signal (TRICKB) such as E) is input to the multiplexer 161.
Apply to.

Through the above process, the multiplexer 16
The bit string output from 1 is recorded on the tape through a modulator (not shown), which will be described in detail below with reference to FIGS. 17 and 18. First, as shown in FIG. 17, when the variable speed reproduction data is recorded in duplicate, for example, at the time of × 6 speed, when the tracking is started at the 1-1 position and when the tracking is started at the 1-5 position, the head is moved once. Since "A ₁ -A ₂ -A ₃ ... A ₁₆ " is all reproduced by the rotation, even if the double speed is started at an arbitrary position, the entire trick area can be reproduced.

Here, among the Ai reproduced on each track at × 4 × speed and 2 × speed, Ai reproduced on the same track.
However, since the same data is recorded in duplicate, only one Ai in the detected Ai is used. Therefore, × 6 ×, × 4 × speed, by constituting the speed video Similarly, in _{"A 1 -A 2 -A 3 -A 4} ... " to × 2 speed, image quality is not improved at low speed.

In order to solve such a problem, the present invention includes two memories, A frame buffer 154A and B frame buffer 154A, which respectively store data for variable speed reproduction, and has an appropriate multiplexing timing as described above. use. That is, at low double speed, the variable speed reproduction data is recorded in duplicate on each track as shown in FIG. 18 in consideration of image quality improvement. Where Ai (i =
1, 2, ..., N) is an area in which the variable speed reproduction data stored in the A frame buffer 154A is recorded in duplicate, and the MRA corresponding to Bi (i = 1, 2, ..., N) is the B frame buffer. This is an area in which the variable speed reproduction data stored in 154B is recorded redundantly. That is, the variable speed reproduction data output from the A frame buffer 154A and the B frame buffer 154B are alternately recorded in the MRA of each track along the tracks.

Therefore, at the time of x6 speed, the position to start shifting
By "A₁-A₂-A₃… A _N"Plays continuously
Or the "B"₁-B
₂-B₃... B_NIs continuously played and the B frame changes
It will compose a high-speed image. By the way, at double speed
Since the reproducible area per rack is large, "A₁-B
₁-A₂-B₂-A₃-B₃… A_N-B_NLike A
Frame variable speed reproduction data, B frame variable speed reproduction
The data is detected at the same time and the shift images of A and B frames are displayed.
Can be configured.

Therefore, at a low speed, the number of variable-speed images to be reproduced is increased as compared with the system shown in FIG. 17, so that the resolution on the time axis is improved and the image quality at a low speed can be improved. Assuming that the number of bits used to form one frame of a shift image at the time of shifting is 576 kbps, when the data for variable-speed reproduction is recorded for every eight synchronous blocks per track, the intra-frame of about 120 tracks is recorded. The variable speed reproduction data extracted from the bit string is recorded. Here, the extracted variable speed reproduction data includes a direct current component (DC), two or three low frequency coefficients, and header information.

Therefore, at a speed of × 6, the number of sync blocks reproduced per revolution of the head is 192 (8 sync blocks × 6 × 2 × 2), and the sync blocks detected per second are The number is 5760 (30 × 192).
Therefore, since the variable speed reproduction data per frame is about 960 synchronization blocks (about 576 kbps), the variable speed video of 6 frames per second is required. Further, since a shift image of 4 frames per second at x4 speed and a frame of 2 frames per second at x2 speed are required, a shift image with high image quality can be obtained at lower speeds.

[0063]

As described above in detail, the present invention is
The present invention relates to a recording system and a recording device on a tape which enables high speed forward / backward reproduction in a digital VCR which records and reproduces a digital HDTV signal compressed based on PEGII. The user can change the speed at any time. It can be started, no additional tracking algorithms are required, variable speed video can be constructed for multiple speeds, and image quality improvement is obtained, especially at low speeds. Further, the variable speed reproduction data can be detected stably even with respect to the non-linear tracking generated by the head / tape mechanism.

[Brief description of drawings]

FIG. 1 is a block diagram of a recording device for variable speed reproduction of a VCR for digital HDTV according to the present invention.

FIG. 2 is a digital HDTV VC to which the present invention is applied.
It is a figure which shows the basic specifications of R.

FIG. 3 is a schematic diagram of a 2 × 2 CH head applied to the present invention.

FIG. 4 is an explanatory diagram of a reproduction area according to the present invention (A).
Is an explanatory diagram for a reproduction region at × 2 × speed, (B) × 4 × speed, and (C) is a reproduction region at × 6 × speed, and (D) is × 2, × 4, ×.
FIG. 6 is an explanatory diagram of a region that is always reproduced in a track at 6 × speed.

FIG. 5 is a diagram showing the number of synchronization blocks reproduced at each speed according to the present invention.

FIG. 6 is a table showing the number of sync blocks reproduced at × 2, × 4, and × 6 speeds according to the present invention.

FIG. 7 is an explanatory diagram of a recording position of variable speed reproduction data with respect to tracking nonlinearity.

FIG. 8 is an explanatory diagram of a trick area per track and a normal area set according to the present invention.

9 is a flowchart illustrating a process of separating a video bit string in the system decoder unit of FIG.

10 is an exemplary diagram of a picture code type applied to the video header decoder unit of FIG. 1. FIG.

11 is a flowchart illustrating a process of separating a bit string of an intra frame in the video header decoder unit of FIG.

12 is a flowchart illustrating a process of separating a bit string of an intra frame in the video header decoder unit of FIG. 1 when the number of GOPs is constant.

13 is a flowchart illustrating a process of aligning bytes in the byte aligning unit of FIG.

14 is a flowchart showing a process of forming a variable speed reproduction bit string in the video bit string processing unit of FIG. 1. FIG.

15 is an explanatory diagram of input signals of the multiplexer shown in FIG. 1. FIG.

16 is a timing diagram for multiplexing of the multiplexer of FIG. 1, (A) 35 per track;
2 synchronization block pattern diagram, (B) waveform diagram of head switching pulse, (C) waveform diagram of normal signal,
(D) is a waveform diagram for the trick A signal, and (E) is a waveform diagram for the trick B signal.

FIG. 17 is an explanatory diagram of a format recorded in an A ₁ trick area on a tape according to the present invention.

FIG. 18 is an explanatory diagram of a format recorded in the A ₁ / B ₁ trick area on the tape according to the present invention.

FIG. 19 is an explanatory diagram for a head trajectory of a general VCR, FIG. 19A is an explanatory diagram for a head trajectory in a reproduction mode of a general VCR, and FIG. 19B is an explanatory diagram for a head trajectory in a variable speed reproduction mode of a general VCR. is there.

FIG. 20 is a block diagram of a recording device of a general home digital VCR.

FIG. 21 is a diagram illustrating a format of a synchronization block.

22A and 22B are explanatory diagrams of a head locus of a general home-use digital VCR, FIG. 22A is an explanatory diagram of a head locus of a trick plate rack system, and FIG. is there.

[Explanation of symbols]

 110 ... Normal reproduction bit string processing unit 111 ... Error correction coding unit 112 ... Normal interleaver 113 ... Sync block forming unit 114 ... Buffer 120 ... System decoder unit 121 ... Transport decoder 122 ... Buffer 130 ... Video bit string processing unit 131 ... Video Header decoder 132 ... Buffer 133A ... A frame memory 133B ... B frame memory 134 ... Variable length decoder 135A ... Buffer 135B ... Buffer 136 ... Run length code selection section 137 ... EOB insertion section 138 ... Byte alignment section 139 ... Variable-speed reproduction bit string formation Unit 140 ... System encoder unit 141 ... Transport encoder 142 ... Bit rate control unit 143 ... Stuffing unit 150 ... Recording format processing unit 151 ... Error correction code Conversion unit 152 ... Trick interleaver 153 ... Synchronization block forming unit 154A ... A frame buffer 154B ... B frame buffer 160 ... Track recording format unit 161 ... Multiplexer 162 ... Track recording format unit

Claims (11)

[Claims] 1. A normal reproduction bit string processing unit for converting an input HDTV bit string into a recording format of a video cassette recorder (VCR) and supplying a normal reproduction bit string, and a video bit string only from a transmission layer of the input HDTV bit string. A system decoder unit for separating the variable speed reproduction data from the video bit string separated by the system decoder unit and converting the extracted variable speed reproduction data so as to match the video syntax, A system encoder unit for reconstructing the variable speed reproduction data output from the video bit string processing unit into a transport packet, which is a transmission standard, according to the header information output from the system decoder unit, and a variable speed reproduction output from the system encoder unit. Data for VCR recording Recording format processing unit that stores each in a corresponding frame buffer, and the normal reproduction data output from the normal reproduction bit string processing unit or the variable speed reproduction data output from the recording format processing unit at an appropriate timing. A digital HD comprising a track recording format section selected for
Recording device for variable speed reproduction of VCR for TV. 2. The system decoder unit includes a PID (Packet I) included in an input HDTV bit string.
and a first decoder for temporarily storing the header information output from the transport decoder, the transport decoder recognizing the identification data) to separate the video bit sequence and extracting the system header information from the input HDTV bit sequence. The digital HDTV VC according to claim 1, characterized in that
Recording device for variable speed reproduction of R. 3. The video bit string processing unit extracts a video bit string of an intra frame from the video bit string output from the system decoder unit, and a sequence or GOP (Group Of Picture) output from the video header decoder. ) A second buffer for storing header information, an A frame memory and a B frame memory for respectively storing a bit string of an intra frame output from the video header decoder, and a bit string output from the A frame memory or the B frame memory. A variable length decoder for decoding according to a variable length method, a third buffer for storing the picture header information decoded by the variable length decoder, and a third buffer for decoding the picture header information decoded by the variable length decoder. A fourth buffer that stores slice header information and macroblock coding information, and a codeword of each block included in the bit string decoded by the variable length decoder, have preset important data for the structure of the variable-speed image. A run-length code word selecting section for selecting the number of run-length code words generated, and an EOB inserting section for adding an EOB (End Of Block) code to the variable speed reproduction bit string output from the run-length code word selecting section. And a byte aligning unit that aligns each byte so that the variable-speed reproduction bit string output from the run-length code word selecting unit has the same configuration as an HDTV bit string, and stores the bytes in the second, third, and third buffers. The bit string output from the run-length codeword selection unit is converted into an HDTV video by using the header information thus generated. 2. A recording device for variable speed reproduction of a digital HDTV VCR according to claim 1, further comprising a variable speed reproduction bit string forming section reconfigured so as to match the syntax of the deo bit string. 4. The system encoder section adjusts the bit rate of the data extracted by the video bit string processing section so that the shift data is extracted in accordance with the area assigned by the shift data. A bit rate control unit with a preset number of code words, and a stuffing unit that adds a null packet when the extracted data is smaller than the assigned bit number under the control of the bit rate control unit, and the system decoder And a transport encoder that reconstructs the variable speed reproduction data output from the video bit string processing unit into a transport packet that is a transmission standard using the header information output from the video bit string processing unit. 1. A recording device for variable speed reproduction of a VCR for digital HDTV described in 1. 5. The error correction coding unit that inserts redundant bits for error correction into a bit string output from a transport encoder, and the recording format processing unit outputs a bit string output from the error correction coding unit. A trick interleaver that performs interleaving, a sync block forming unit that converts an output bit string of the trick interleaver into a sync block form, and a shift image for each frame applied from the sync block forming unit are stored. 2. A recording device for variable speed reproduction of a VCR for digital HDTV according to claim 1, wherein the recording device comprises an A frame buffer and a B frame buffer. 6. The track recording format section receives a head switching signal which is a drum rotation control signal,
A recording timing generation unit for outputting a multiplexing timing signal, a normal timing signal, a trick A timing signal and a trick B timing signal, normal reproduction data, and A frame shift data output from the frame buffer of the recording format processing unit. And B
2. A VCR for a digital HDTV according to claim 1, further comprising a multiplexer for receiving frame shift data and multiplexing the input data by controlling a timing signal output from the recording timing generator. Recording device for variable speed reproduction. 7. The video header decoder stores header information in a buffer by comparing a sequence start code and a picture start code to extract an intra frame bit string from an input video bit string, and stores the header information in a buffer. 4. The digital HDT according to claim 3, wherein the intra frame is extracted using the signal, and the extracted intra frame is stored in the A frame memory or the B frame memory.
Recording device for variable speed reproduction of VCR for V. 8. The video header decoder stores header information in a buffer by comparing with a sequence start code and a picture start code in order to extract a bit sequence of an intra frame from an input video bit sequence, and counts the header information in a buffer. 4. The intra frame is extracted by comparing the number of frames with a preset period in which the intra frame is generated, and the extracted intra frame is stored in the A frame memory or the B frame memory. Recording device for variable speed reproduction of VCR for digital HDTV. 9. The byte alignment unit extracts a variable-speed reproduction bit string from an input intra-frame bit string, confirms a slice start code, stores header information in a buffer, and stores [8-{(the run 4. The digital HDTV according to claim 3, wherein only the number of bits of the codeword selected by the length codeword selection unit + the number of bits of the DC component) mode 8}] are stuffed.
Recorder for variable speed reproduction of VCRs for automobiles. 10. An HDTV bit string is input and normal reproduction data used during normal reproduction is stored in a normal area.
In a digital VCR that records variable speed reproduction data used during variable speed reproduction in a trick area, variable speed reproduction can be performed on an arbitrary track according to a set maximum speed number × N (N = 2, 4, 6 ...). When it starts
The area of the M part that can be always reproduced is the trick area Area
(N), the minimum area of the trick area Area (N) is set as a basic unit of a trick area assigned to one track, and the extracted variable speed reproduction data is used for the trick of the M portion existing in one track. A recording method for variable speed reproduction of a VCR for digital HDTV, which is characterized by performing redundant recording in an area. 11. An HDTV bit string is input and normal reproduction data used during normal reproduction is stored in a normal area.
In a digital VCR that records variable speed reproduction data used during variable speed reproduction in a trick area, variable speed reproduction can be performed on an arbitrary track according to a set maximum speed number × N (N = 2, 4, 6 ...). When it starts
The area of the M part that can be always reproduced is the trick area Area
(N), the minimum area of the trick area Area (N) is set as the basic unit of the trick area assigned to one track, and the extracted variable speed reproduction data of the A frame and the variable speed reproduction data of the B frame are set. Of the trick areas of the M part, the trick areas of the M / 2 part are respectively allocated, and the variable speed reproduction data of the A frame or the variable speed reproduction data of the B frame is alternately recorded in one track and is redundantly recorded. A recording method for variable speed reproduction of a characteristic VCR for digital HDTV.